Gelled Diesel: How do I fix this?
 

A couple of nights ago the temperature dropped below zero and stayed that way until today. After that first night, my 1981 300D wouldn't start in the morning. It's hooked up to a block heater, but it doesn't seem to be doing much, as the car still won't start (actually won't even turn over:(). What does this mean and how can I fix it?

Thank you all!

How do you know the diesel is gelled? Where are you located and where did you get the fuel from? Around here, diesel from the pump is good down to -30F.

Me thinks the problem lies elsewhere. How are the glow plugs?

I'm located in Jackson, MI. I suppose I assumed it was the diesel gelling because I've always heard it tends to do so quite easily and I've read other posts about people with various diesel cars experiencing the same problems (no turning over after a cold night) and figured this was likely the problem as the car was running fine the day of that first cold night, but not the next morning.

If your engine isn't even turning over then you have an issue other than a fuel issue. Is the engine trying to start and just not catching or is it not even turning over.
If you do have a gel problem generally the filter is where gelled fuel will cause an issue. A new filter might solve the issue.

The engine isn't turning over at all. I've had problems nearly identical to this before when it's been cold out, where the engine will try to start but won't catch. Overtime as I would continue to try to start the engine, it would make less and less of an effort, until it wouldn't even turn over, just like now. In the past, plugging the block heater in has always fixed this problem, so I assumed it had something to do with the fuel.

If it won't crank/turn-over, the battery is the first problem. Charge or replace your battery. If it won't stay charged or won't charge from driving, you have electrical problems.

Fuel here in Michigan is fine at 0F, it has been well above that during the day also, so I doubt that is your problem.

Diesels fire from the heat of compression. The faster you crank, the more heat it produces and the more likely to start. Bad starter/battery/alternator/wiring can all contribute to slow cranking and that will often result in a no-start when it's cold.

Synthetic oil also helps in the winter as it allows the engine to crank more easily, and the block heater will help with heat and cranking speed.

I just recently replaced the battery. Is it possible for the battery to freeze or something of the sort? I'm just thinking outloud.

Batteries are just a chemical reaction. Lower the temperature and you lower the power output of the battery.
In cold weather you have many things working against you. Lower power from battery, viscous oil, lower combustion chamber temp. All these things make it difficult to start. I would start by putting a charger on your battery. Once charged, if it still won't turn over, take it to a parts place and have them test it.

Possible semantics problem here
 

I've noticed lots of car people have a different idea of what "turn over" means. To me if the starter motor is rotating the crankshaft the engine is turning over. But to some guys "won't turn over" means the fuel isn't exploding and the engine isn't starting to catch and run on its own.

It makes a big difference in troubleshooting, 'cause in one case it's a battery/cables/starter issue, in the other case a possible glow plug/air in lines problem.

Your owners manual says to add kerosene to prevent gelling.

Danny

X2.

We go off on tangents all the time because proper terminology of "won't crank" and "cranks but won't start" is not utilized.

"Turn over" has proper usage as well...........but not on a vehicle.:D

The manner in which im using the word (not sure if it's the appropiate one) refers to the engine not doing anything when I attempt to start her up. All that happens is a little "click".

Mmmm turnover.

That would be a dead battery or a bad starter. Not gelled diesel. We have winter diesel here in MI, good to down around -25F or so.

Not to winter blend diesel, only #2 diesel which you can't find in any northern states in the fall/winter.